Call transmitter



July 4; 1944. R. F. MALLINA ,35

' CALL TRANSMITTER Filed Aug. 8, 1941 Kl FIG. 2

lA/VENTOR REMALL/NA 1 y @(ac Ar TORNEY Patented July 4, 1944 UNITED STATES F v j assent" lf I CALL TRANSMITTER" V V iRudolph F.1Mallina, Hastings on l iudsonphl. Y.', I

, assig nor to Bell Telephone Laboratories, In corporated, New York, N. Y., acorporation of a New York ApplicationAug-ustS, 1941,-Serial No. 405,897

" 3Qlaims. (01. 1795-9 j Th-isinvention relates to telephone call trans mitters of thetype in-which the release of 'manua-l-ly pre'tensioned reeds by the operation of manually operable digitkey members and their consequent vibration-between the pole-pieces of an alternating current generator is efiective -t'o transmit-signals in a telephoneline connected thereto corresponding to'the digits of the keys depressed forcontrolling the operation of selector and connector switches at the telephone exchange 'for' establishing --talking connection.

It isan improvement-over-the call transmitter disolose'ddn a copending application Serial 'No. 325 347, filed in-the name'of R. F.-Millina, March 22, 1940, now Patent No. 23151344, granted March 30, 1943.

In the above-mentioned application, a call transmitter is disclosed having an operative mechanism for the vibrative elements of an alternating current generator in which pivoted pawl-like -members are moved upon the return movement of-the keys to normal in juxtaposition of the underside of the vibrative elements by rib bon shaped retractilesprings secured to arms carried by so-ca'lled U-shaped bars, which are operated in predetermined combination by the operation of the keys. In the use of this-mechanism, it was found that upon the return movement of the keysand the U-shaped bars to normal followed by. the movement of the pawl-like members as efiected by the tension of the respective retractile ribbon springs =movable with the U-shaped bars, caused these pawls to be pressed againstthe free ends of the vibrative elements prior to their'coming to rest andduring the movement .of these elements toward their pretensioned positions, with the consequent shortening;-oflthe..operating period of time of the elements and causing undue wear between the elements and their releasing pawls.

,The'objectof this invention is the provision of an operating mechanism in which a pawl-like member which is common to all the vibrative elements is moved by the movement of the keys in position relative to the elements in a sequence offlsimple and positively controlled operations, thus-avoiding (interference between --the pawllike, members; and the vibrative elements resulting; in .a greater: number of positive operations of. the, transmittermecha'nism. a I

- Other-novel features and advantages ofithe invention will appear irom the following description and .by the claims appended ther'eto,

in-g lini.which:

Fig. 1 is a side elevation view of the -trans-' mitter mechanism shown with the keys and operating parts actuated therebyin normal nonoperated position, the casing for housing the transmitter mechanism and the base plate-being shown in vertical section and withlportions broken away; I r p v Fig. 2 is a partial top view of Fig; 1 showing the operative relation of the U-bars and thekey members, the keys being shown with portions broken away; I

Fig. '3 is a view similar to Fig. 1 butyshowing one'of the keys and a number of operating "parts controlled thereby artly operated;

Fig. 4-is a view similar to Fig, --3 but showing such key and operating parts controlled thereby in their full operated position; and i Fig.' 5 is a view similar -to'that -of Figs. 1A3 and 4 but showing the operating parts in pojsi tion following the return of the operated key to normal position. 5

According to theinvention a set of ten key members'representing digits from 1 to 9 plusa zero of the type as shown by keysKl, K6 and K1 is provided for actuating five U-ehaped barsZB-l, B2, B3, B4 and B5 as described in the abovementioned application in ten predetermined combinations-through the engagement of lugs, as Ll, carried by key Kl, for example, engaging as shown in Fig. 2 the bars B2 and B4. The common lug L2 carried by key K6 engaging the U- shaped bars BI and B2 and the pair of lugs L3 carried by key K1 engaging the 'U-shaped bars B3 and B5; the remaining keys (notshown), as mentioned in connection'with keys Kl, K6 and K1 actuating the bars Bl, B2, B3, etc., in cornbinations so as to produce a difierent signal for each of the keys, all the keys being yieldably held in normal non-operated position by retractile springs as 26 having one of their ends hooked to lugs -formed with the body portion of the keys and 'their'other ends hooked/to a common plate 21 formed with and extending perpendicularly from a supporting plate 22.

The set of key members Kl,- K2 K3, etc., and the U-shaped bars B|, B2, B3, etc., actuated thereby are pivoted on a common shaft 25 journaled at both ends in upright supporting members as 24 formed; with the supporting plate 22. On shaft 25 is'pivoted the arms I!) of a bar. extending in direction transverse of the keysa'nd held in operative relation with lugs as L Y car; ried by the keys by the tension of a retractile spring RS having one of itsends hooked to an (all upright support- -US secured to the supporting plate 22 and its other end to the arm In of bar II. The free end of one of the arms ID as shown in the drawing is provided with an upwardly projecting lug l2 disposed in engageable relation with the horizontally disposed side of a pivoted bar N5 of angular cross section, the vertically disposed side of this bar extending in juxtaposition to the underside and free ends of a plurality of vibrative elements in the form of tuned reeds RI, R2, R3, R4 and R5, the angle bar l6 having a stud, as H, at each end freely engaging bearings in upright supporting members l8 and I9 formed with the mounting plate 22.

To the U-shaped bars Bl, B2, B3, etc., are secured as by rivet l3, the arms C5, C4, C3, C2 and Cl respectively. These arms are formed at their free ends with similar projections l4 and I5, projections l4 being disposed in operative relation with the horizontally disposed side of angle bar I6, while the projections l5 are disposed in engageable relation with the free ends of reeds RI, R2, R3, R4 and R5 for tensioning them through the tension of retractile springs 28 when the keys and the U-bars BI, B2, B3, etc., are in normal non-operated position, the springs 28 having one of their ends hooked to the upright extending plate 21 and their other ends to upward extending lug portions 20 formed with the arms Cl, C2, G3, etc.

' A spring 2| of arcuate cross section and common to all the arms CI, 02, C3, etc., is disposed withits parallel edges bearing on the plate 22 and its apex in engageable relation with downwardly projecting lugs 30 formed with the arms Cl, C2, C3, etc., so as to control the manual operation of the set of key members Kl, K2, K3, etc., in a manner which will be hereinafter described in detail.

The vibrative elements RI, R2, R3, etc., are clamped between the blocks 45 by a number of screws 5| and extend into an opening in a coil 4| for vibration between the poles X and XI of a permanent magnet PM and in engageable relation with the lugs l5 of arms Cl, C2, C3, etc., and with the vertically disposed side of pivoted angle bar I6 as above mentioned.

In a typical example of operation of the transmitter mechanism above described, considering the operating partsin the position shown in Fig. 1, i. e., wherein the reels RI, R2, R3, etc., are held in flexed position by the engagement of lugs [5 of arms Cl, C2, C3, etc., with reeds R5, R4, R3, etc., under the tension of springs 28, the operation of key member K5, for example, from the position shown in Fig. 1 to the position shown in Fig. 3 is effective to impart a pivotal movement to the U-shaped bars BI and B2 through the engagement of lug L2 of that key and a pivotal movement to the transverse bar I I through the engagement of lug LY of key K6 with that bar. The simultaneous downward movement of U-shaped bars BI and B2 and the arms C5 and C4 carried by these bars is effective to release the reeds R5 and R4 while the projections I4 of these arms are now positioned in engagement with the top surface of the horizontally disposed side of bar l6 prer paratory to the rotation of this angle bar for moving its vertically dis-posed side out of engageable relation from the reeds RI, R2, R3, R4 and R5 so as to permit the release and vibration of reeds R4 and R5 upon the continued operation of key K6 from the position shown in Fig. 3 to the position shown in Fig. 4, the pivotal movement of angle bar lfibeing timed to occur following the movement of transverse bar H as effected by the lug LY carried by key K8 for moving the projection 12 of arm ID of that bar a predetermined distance from the angle bar l6, thus permitting the pivotal movement of the latter through its engagement with the lugs M of arms C4 and C5 operating in combination with the manual operation of key K6 while the reeds RI, R2 and R3 remain tensioned due to their en agement with the lugs l5 of their unoperated arms Cl, C2, and

- C3 held by the tension of their retractile springs 28. The pivotal movement of angle bar I6 and the consequent release of reeds R4 and R5 permit the vibration of these reeds between the poles X and XI of the alternating current generator for transmitting a signal in the telephone line connected to the coil 4! of frequencies corresponding to the depressed key K5 and the operating parts of the transmitter are now in the position shown in Fig. 4.

Upon the return movement of the depressed key K6 from its full operated position'shown Fig; 11; to the position shown inFig. 5ifol lowed by th e return movement of the .U-shaped bars BI and- B2 and therefore that of the arms C5 and C4, the lugs {5 of these arms move the reeds R4 and R5 to their tensioned position which is reached prior to the pivotal movement of angle bar [6 toward normal position as affected by the engagement of lug 12 of bar ll itself operated by the-tension of its retractile spring RS but under the control of the key K6 so that the vertical side of angle bar 16 does not come into contact with the ends of these reeds during their tensioning operation,

thus avoiding the consequent wear and interference between these parts resulting in a greater number of positive operations of the transmitter mechanism, the function of the arcuated spring 2| being to offer maximum resistance to a pressure applied on any one of the keys during their operation as from the position shown by key K6 in Fig. 1 to the position of that key in Fig. 3 where the resistance of this spring decreases to a negligible value tending to induce the operator to depress the keys to their maximum limit of-movement.

What is claimed is:

1. In a call transmitter, a set of keys, vibrative elements, operable means controlled by the opera! tion of said keys and having retractile springs for normally tensioning said elements, an operable common latching member for said elements, another operable means movable independently of the first-mentioned operable means by the operation of any one of the key members and having aretractile spring-for moving said common latching member in position for retaining said elements tensioned upon a predetermined manual movement of said keys and means carried by the firs-t mentioned operable means for actuating said latching member upon the continued operation of said keys and the disengagement of the second mentioned operable means from said latching member for releasing said elements to cause their vibration. Y v 2. In a call transmittena set of key members, a plurality of U-shaped bars disposed for operation in predetermined combinationsbythe movement of said key members, a plurality of. .vibrative elements, a pivoted .angle..bar,;a bar disposed for operation by any one of, said key members and having means for normally positioningvsaid angle bar to hold said elements in pretensioned said key members, an arm carriedbyleachof.

said U-shaped bars, each of said arms having means for engaging one of said elements for moving them in said pretensioned position, other means carried by said arms disposed in engageable relation with one side of said angle bar for rotating it upon the operation of any one of the key members for releasing the elements corresponding to the U-shaped bars actuated by that key, the third-mentioned bar restoring said angle bar in the vibrating path of said vibrating elements following the tensioning of the latter by the first-mentioned means carried by said arms.

3. A call transmitter having vibrative elements, a mechanism for controllin the operation of said elements, said mechanism comprising a set of key members, a set of movable bars disposed for operation by the movement of said key members,

a retractile spring for each of said movable bars for holding them in operative relation with said key members, means carried by each of said bars for tensioning said vibrative elements under the tension of said retractile springs, a pivoted latching element of angular cross section, a pivoted bar disposed in operative relation with each of said keys, a retractile spring for said pivoted bar for yieldably holding the latter in operative relation with said key members and said latching element in engageable relation with said vibrative elements under the tension of said retractile spring when said elements are in their tensioned position, other means carried by each of said movable bars for rotating said latching element following the operation of the pivoted bar for disengaging it from said elements for permitting their vibration.

RUDOLPH F. MALLINA. 

